[GHC] #3456: Add FilePath -> String decoder

[GHC]

#3456: Add FilePath -> String decoder
-----------------------------+----------------------------------------------
Reporter:  judahj            |          Owner:                  
    Type:  proposal          |         Status:  new             
Priority:  normal            |      Component:  libraries/base  
 Version:  6.10.4            |       Severity:  normal          
Keywords:                    |       Testcase:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
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 Currently, !FilePaths on POSIX systems are represented as raw
 bytes in a String.  When this last came up on the mailing list, the
 general
 consensus was to make !FilePath an abstract datatype representing paths as
 Strings on Windows and raw bytes on POSIX systems.  However, such a change
 is
 sure to break some existing code.

 As a small step towards that goal, I propose adding the following two
 functions
 to the System.IO module:

 {{{
 filePathToString :: FilePath -> IO String
 getFilePathToStringFunc :: IO (FilePath -> String)
 }}}

 This functionality is implemented in the attached patch; Haddock docs are
 here:
 http://code.haskell.org/~judah/new-io-docs/System-
 IO.html#v%3AfilePathToString

 On POSIX those functions decode according to the current locale, so they
 ought to be in the IO
 monad.  I think that the latter function will be easier to integrate into
 existing pure code.

 On Windows, those functions are just `return` and `return id`,
 respectively, since GHC already treats
 !FilePaths as Strings on that platform.

 Discussion deadline: September 9

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3456>
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